package org.codehaus.mojo.properties;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/**
 * ExpansionBuffer implementation that allows processing of default values within property placeholders
 *
 * @author tdiamantis
 */
public class DefaultValuesAwareExpansionBufferImpl extends ExpansionBuffer {
    public DefaultValuesAwareExpansionBufferImpl(String unresolved) {
        super(unresolved);
    }

    public KeyAndDefaultValue extractPropertyKeyAndDefaultValue() {
        advanceToNextPrefix();

        discardPrefix();

        String key = beforeNextSuffix();

        String defaultValue = defaultValue();

        discardToAfterNextSuffix();

        return new KeyAndDefaultValue(key, defaultValue);
    }

    protected String beforeNextSuffix() {
        int defValuePos = unresolved.indexOf(":");
        int propertySuffixPos = unresolved.indexOf("}");

        // check default value separator only if before next suffix
        if (defValuePos != -1 && propertySuffixPos != -1 && defValuePos < propertySuffixPos) {
            return unresolved.substring(0, defValuePos);
        }

        return unresolved.substring(0, propertySuffixPos);
    }

    private String defaultValue() {
        int defValuePos = unresolved.indexOf(":");
        int propertySuffixPos = unresolved.indexOf("}");
        if (defValuePos != -1 && propertySuffixPos != -1 && (defValuePos + 1) < propertySuffixPos) {
            return unresolved.substring(defValuePos + 1, propertySuffixPos);
        }

        return null;
    }
}
